This invention relates to a shed forming device, such as for instance a jacquard machine, comprising at least one shed-forming element to determine the positions of one or more warp yarns on a weaving device, a lifting means provided for moving up and down the shed-forming element, and at least one actuator provided for selectively influencing the shed-forming element, so that it either stays at a fixed height, or is moved by the lifting means.
More particularly this invention concerns a weaving device provided with a shed-forming device according to this invention.
In addition, a shed-forming element (e.g. a hook) for determining the positions of one or more warp yarns on a weaving device, which has been provided for being selectively influenced by an actuator of a shed-forming device, is within the scope of this invention. More particularly such a shed-forming element has then been provided to be selectively influenced by an actuator or/and a shed-forming device according to this invention.
Shed-forming devices with the characteristics mentioned above are well known and are mainly used to form a shed during successive weaving cycles on a weaving machine each time between a series of warp yarns, in which the warp yarns take up such a position with respect to one or more inserting levels, that after having inserted the weft warp yarns on this inserting levels a fabric is formed having the structure desired and possibly the design or pattern desired.
A known shed forming devicexe2x80x94which has been described in GB 2 047 755xe2x80x94is a two-position-open-shed jacquard machine on which the warp yarns may be brought at two heights and which allows during each cycle either to keep those warp yarns (according to the open-shed principle) at the same height as during the preceding cycle or to bring them at a different height, as desired.
For that purpose, this device disposes of two knives which may be moved up and down in opposition and a series of sets of two co-operating shed-forming elements, called hooks, which may be moved up and down by a respective knife and which in their upper position may be elastically deformed by means of electromagnets in order to hook on to a holding lutch provided for at a fixed height. The shed-forming elements are connected to each other by a pulley cord thrown around and led under a pulley of a pulley element. The pulley element itself is connected to one or more harness cords, which, in turn, are connected to their respective warp yarns.
By making the hooks and the knives moving up and down or by selecting one of the hooks in its upper position, so that it is held in the upper position, the warp yarns my be brought into or kept in one of two different positions during each cycle.
In EP 0 214 075 a similar two-position-open-shed shed-forming device is described. This device differs from the device described above, in that the pulley element now comprises an upper and a lower pulley, where the pulley cord, connecting the two hooks is thrown around the upper pulley and a second pulley cord is thrown around the lower pulley from a fixed fastening point and is further connected to the warp yarns and in that the selection of the hooks in their upper position may now occur by an elastic deformation of two strips with hook-shaped extremities by means of an electromagnet.
Both devices function with a pulley device and pulley cords. This system has several disadvantages. Rolling the pulley cords off the pulleys causes the pulley cords to wear out so that they might break easily. The pulley elements function in the dusty environment of a weaving mill, as a result of which they will get jammed by the effect the dust has on their bearings. At the high working speed of modern weaving machines, the pulley devices develop frictional heat, which has a negative influence on the duration of the pulley cords and a ventilation device should be provided for, in order to evacuate this heat. Furthermore replacing parts of these pulley device (pulley cords, pulley elements) in case of break or wear is a particularly time consuming job.
The first purpose of this invention is to provide for a shed-forming device for a weaving device, having none of the disadvantages mentioned above.
There are shed-forming devices which function without a pulley device and which do not show the above-mentioned disadvantages. Such a pulleyless shed-forming device was described, among others, in EP 0 779 384.
This shed-forming device works with a U-shaped flexible hook, which is connected to one or more harness cords without a pulley element intervening and of which the upper part of the two legs has the shape of a hook and on which respective knives may hook to be moved upwards, with the hook resting on a bottom board. The knives move up and down in opposition. An electromagnet, situated between de legs of the hook is used to bend the hooks elastically towards each other, so that the hook-shaped extremities of these legs get outside the pick-up range of the knives. In BE 9800036 and BE 9800035 also, similar shed-forming devices are described.
However, these pulleyless devices have a new problem, namely when a hook is coupled with one leg to a rising knife, then the other descending knife will hit the top of the other leg of the rising hook, and when one leg of a hook is coupled to a descending knife, then the other rising knife will pick up again the descending hook at the hook-shaped extremity. To avoid these unwanted phenomena, the known devices provide for a supplementary control with the intention to make the hook leg concerned give way in these critical moments.
This avoiding movement has to be performed each time at full speed of the moving hook. This makes the control rather complicated and consequently the moving hooks will suffer from supplementary friction with more production of neat. Moreover, the devices described are insufficiently suitable to adapt the lifting of the hooks and to adjust the inclination of the shed to be for med.
In addition, the electromagnet is expected to influence the position of a hook leg over its entire length. For that purpose, a rather large passing space is needed for the hook legs as a result of which the electromagnets have to work with a rather large air gap and as a result of which the selection system is no longer able to function with sufficient efficiency. In order to increase efficiency, stronger electromagnets are needed, but they have the disadvantage that they consume quite some electric energy.
A second purpose of this invention is to provide for a shed-forming device with the help of which the disadvantages of the known pulleyless shed-forming devices mentioned above may be remedied.
According to this invention the objects mentioned above are obtained by providing for a shed-forming device comprising at least one shed-forming element to determine the positions of one or more warp yarns on a weaving device, a lifting means provided for to move the shed-forming element up and down, and at least one actuator provided for to influence the shed-forming element selectively, so that it is either kept at a fixed height or is moved by means of the lifting means, and of which, according to the invention, each shed-forming element comprises at least one selection body which, in order to obtain said selective influencing, may be put, as desired, in a first or in a second stable position by means of an actuator.
Of course, the said aims are likewise achieved by providing for a shed-forming element to determine the positions of one or more warp yarns on a weaving device having the characteristics mentioned above. A shed-forming element that has been provided for to be selectively influenced by an actuator of a shed-forming device and that comprises, according to his invention, at least one selection body, whereas this selection body, for the said selective influencing, as desired, may be put in a first or second stable position by means of the actuator, and is therefore in itself an object of this invention.
Because the said positions of the selection body are stable, it is possible to change the position of the selection body by influencing it temporarily only once by means of the actuator. After the selection body has taken up its required position, no further influencing is needed.
For each co-operating lifting means, each shed-forming element may comprise a different selection body, with which, in the first stable position, it is within the pickup range of the lifting means and is therefore able to rest on the lifting means concerned and in the second stable position will come outside this pick-up range. Each time, a shed-forming element should be moved by a well-defined lifting means, the selection body co-operating with this lifting means is shifted into the first position, whereas each time the selection body not needed at that moment may stay in the second position. With this, the hitting problem mentioned above may be solved without any friction and in a particularly efficient manner. Moreover, the actuator may be carried out such that it only consumes energy when it moves a selection body into an other position. Therefore, such a shed-forming device is moreover particularly economic as far as energy is concerned.
The actuator may further be carried out in such a way, that it comprises a part that is movable by an electromagnetic force which in turn is provided for to transfer a mechanical force to a selection body in order to change the position of this selection body. The bobbin and the movable part are both part of the actuator, which may be installed as a separate unit, apart from the shed-forming element, so that a minimal air gap may be provided for.
Furthermore, the lifting height of the shed-forming elements may also be rather easily changed with a similar shed-forming device. In addition to the change of the lifting height of the knives, it is indeed sufficient to change the height setting of the actuators in a corresponding manner. The actuators of a same device may be set at different lifting heights rather easily, what may be needed when an inclination of the shed to be formed is adjusted (where, for instance, the lifting height of the hooks is gradually increasing from front to back in the shed-forming device). It is indeed sufficient to install these actuators on a supporting construction, which may be installed in a corresponding inclined position.
Therefore a shed forming device according to this invention may be carried out and function without a pulley device so that the problems mentioned above with respect to pulley devices are remedied on the one hand, but on the other hand making it possible that the danger of the knives hitting the hook may be avoided in a very simple and effective manner without this causing any disadvantages and more particularly without the disadvantages described above connected to the known actuator control to make the hook give way and moreover it is much better suitable for an adaptation of the lifting height of the shed-forming elements to be carried out and for adjusting an inclination of the shed to be formed.
The shed-forming device according to this invention on the one hand and the shed-forming element according to this invention on the other hand are preferably carried out in such a way that the selection body is movable between two end positions with respect to the shed-forming element, and that the shed-forming element comprises a push means which is provided for transferring a mechanical force to the selection body, in order to change the position of the selection body. The bobbin and the movable part are both part of the actuator, which as a separate unit, apart from the shed-forming element, may be installed, so that a minimal air gap may be provided for.
Furthermore, also the lifting height of the shed-forming elements may be changed rather easily with a similar shed-forming device. It is indeed sufficient to change the installation height of the actuators in a corresponding manner in addition to a change of the lifting height of the knives. The actuators of a same device may likewise be installed at different lifting heights rather easily, what may be needed when an inclination of the shed to be formed has to be adjusted (the hooks, for instance, obtaining a gradually increasing lifting height from front to back).
It is indeed sufficient to install those actuators on a supporting construction, which may be put in a corresponding inclined position.
Therefore a shed-forming device according to this invention may be implemented and function without a pulley device on the one hand, so that the problems mentioned above with respect to pulley devices are remedied, on the other hand, makes it possible, in a very simple and efficient manner, to avoid that the knives might hit the hook and that without causing any disadvantage and more particularly without causing the disadvantages described above, involved in the known actuator control to make the hook turn aside and is moreover much better suitable for an adaptation of the lifting heights of the shed-forming elements and for an inclination of the shed to be formed to be adjusted.
The shed forming device according to the invention on the one hand and the shed forming element according to this invention on the other hand are preferably carried out in such a way that the selection body is movable between to end positions with respect to the shed-forming element, and that the shed-forming element comprises a push means which has been provided to exert a force on the selection body which counteracts the movement of the selection body from any end position in the direction of the other end position, so that the selection body may be kept stable in the said end positions.
A similar shed-forming element may be effectuated with the help of very simple means and at a low cost price, whereas the stability of the end positions of the selection body is yet well assured.
The push means may be a spring for instance, which, on one side is connected to the selection body and on the other side connected to the shed forming-element, so that the spring force exerted on the selection body counteracts the movement of the selection body from any end position.
By a suitable choice of the spring, the stability may be adapted to the in-use conditions of the shed-forming element. The spring force should be sufficient to prevent the selection body from being accidentally moved from one into another stable position (for instance by impacts or chocks). Preferably, a compression spring is used.
In a preferred embodiment, the shed-forming element comprises two stops, which limit the path length of the movement of the selection body and determine the said end positions.
A very reliable shed-forming element to be realized in a particularly simple way, is obtained when each of its selection bodies is installed to face an opening in a wall of the shed-forming element and protrudes through this opening in at least one of its stable positions, and when the said stops are formed by respective edges of this opening.
In a particularly preferred embodiment, each selection body is rotatable between the said stable positions with respect to the shed-forming element.
In a particular embodiment of the shed-forming device according to this invention, each shed-forming element may be selectively influenced by means of at least one actuator whose installation height is variable.
The actuator may be carried out as a separate unit and installed beside the path of the movement of the shed-forming element. If this installation height is variable, the shed-forming device may be very easily adapted to the modified lifting height of the knives. Suffice it to adapt the installation height of the actuators.
This is particularly the case if at least one selection body of each shed-forming element may be selectively influenced by means of at least two actuators installed at different levels, whereas the difference in height between these two levels is variable.
Then the lower actuator is installed, for instance, on the level of a selection body when the shed-forming element has taken up its lower position, whereas an upper actuator is installed at the level of the same selection body when the shed-forming element is in its upper position. When the difference in height between the two actuators is variable, the installation of the actuators is very easily adaptable to a modified lifting height.
Preferably each shed-forming element comprises at least one selection body which has been provided to arrive in a first stable position within the pick-up range of a lifting means, so that the selection body may rest on this lifting means, whereby the shed-forming element is moved to come in a second stable position outside this pick-up range.
Preferably the shed-forming device comprises two lifting means movable up and down in opposition, whereas each shed-forming element comprises two selection bodies which are provided to come in a first stable position within the pick-up range of a respective lifting means, so that the shed-forming element may be moved by the lifting means, and to stay in a second stable position outside this pick-up range.
A similar shed-forming device may be carried out as a two-position-open-shed shed-forming device without pulley device.
The two lifting means may be provided either to move up and down in opposition one above the other, or to move up and down in opposition one beside the other.
In order to co-operate with two lifting means, which are movable up and down in planes situated next to each other, the shed-forming element may be carried out with two legs in which respective selection bodies are provided. A similar shed-forming element is then carried out, for instance, in a U-shape with two parallel legs with respective selection bodies and with a fixing point for a harness cord in the middle of the connecting piece.
In order to co-operate with two lifting means, which are movable up and down one above the other (for instance in a same vertical plane) the shed-forming element may be carried out as an oblong unit in which the selection bodies are provided one above the other. A similar shed-forming element may be carried out in a rod-shaped form with an internal space that is at least partially surrounded by walls. The selection bodies may be provided between these walls. Preferably, an opening for each selection body has been provided for to let the selection body pass, so that it may come within the pick-up range of a lifting means and so that the edges of these openings form stops to limit the path of the movement of the selection body concerned.
Furthermore, this shed-forming device comprises preferably also a holding means for each shed-forming element, provided at a fixed height, while each shed-forming element comprises a selection body which is provided, in a first stable position, to come in a holding position with respect to this holding means, the shed forming element being held at a fixed height by cooperating with the holding means, and to come in a second stable position in a non-holding position with respect to the holding means.
The installation height of this holding means may also be made adjustable, so that the lifting height of the shed-forming elements may be easily modified.
In a particularly preferred embodiment of these shed-forming devices each selection body and each actuator co-operating with it are carried out in such a way that the force exerted by the actuator on the selection body in order to move this selection body from one stable position into the other is exerted in a direction where the force may not be counteracted by a force which is the consequence of a movement of the shed-forming element by means of a lifting means. Because of this, it is avoided that the shed-forming element will counteract the actuator or will even block it.
In a preferred embodiment, each actuator comprises a movable push element with which the selection body may be pushed from the first into the second stable position and the other way round.
Preferably each actuator comprises also a driving means, with which the push element may be moved into a first and a second push position in order to bring a selection body into the first and second stable position respectively, while the push element is provided to take up a neutral position between these push positions when the driving means is not exerting any driving power on the push element.
With a similar actuator, only energy is consumed when the actuator has to move the push element to move the selection body into another position.
By using a similar actuator, this shed-forming device consumes very little energy.
The push element may either be movable in a linear way or be rotatable between the two said push positions.
Preferably, each actuator comprises an electromagnetic driving means for moving the push element. A preferred actuator consists of a plate-like rotor made of ferromagnetic material on which permanent magnets with alternating north and south poles are installed and a number of poles are installed opposite this rotor around which solenoids are installed to generate an axial flux, which, depending on the polarity of the current will make the rotor turn in one or the other direction. Other possible turning actuators function by the principle of motors with radial flux, such as, for instance, the stepper motor. In addition, an ultrasonic piezo motor or a nano motor or linear actuators, such as electro plunger magnets, among others, may be used.
A particularly advantageous embodiment of this shed-forming device comprises a series of shed-forming elements, which, by one or more lifting means are movable in height and a number of holding means to hold these shed-forming elements at a fixed height, while a number of holding means co-operating with different shed-forming elements are part of a same holding construction which may be installed in an inclined position, so that the installation height of these holding means increases gradually in the direction of the inclination.
This embodiment makes it particularly simple to adapt the installation heights of the holding means to the adjustment of an inclination of the shed to be formed.
In an other very advantageous embodiment the device comprises a series of shed-forming elements which are movable in height by one or more lifting means, while an actuator is provided for at least one selection body of each shed-forming element at a height which corresponds to the height of the selection body when the shed-forming element is moved upwards over a lifting height by a lifting means, and while a number of actuators, co-operating with different shed-forming elements are part of a same supporting construction which may be installed in an inclined position, so that the height setting of the actuators is gradually increasing in the direction of the inclination.
This embodiment also makes it very simple to adapt the installation heights of the actuators to the adjustment of an inclination of the shed to be formed.
Preferably, the said holding construction and the said supporting construction are connected to each other or are forming together one unit. Therefore, the holding means and the actuators may be put at the exact heights by one single adjustment.
Preferably, the holding construction and/or the supporting construction may also be placed in a non-inclined position and have a variable installation height so that the device may be adapted to a modified lifting height.
If the said holding construction and/or the said supporting construction may be installed in several positions with a different inclination, the inclination of the shed to be formed may be easily changed.
In a most preferred embodiment of this shed-forming device each shed-forming element is movable between a lower and an upper position by means of a first and a second lifting means which are movable in opposition, each shed-forming element comprises a first and a second selection body, per shed-forming element, there is a first and a second actuator provided to co-operate with a first selection body, when the shed-forming element is in its lower position and in its upper position respectively and per shed forming element, there is a third and a fourth actuator provided to co-operate with a second selection body when the shed-forming element is in its bottom position and in its top position respectively.
In the shed-forming device according to this invention, a number of actuators and/or hooks are provided preferably in a common module or cassette. Such a module or cassette may comprise for instance the actuators for two different rows of hooks. Preferably, these actuators then are installed in two rows back-to-back. Then on both sides of the modules or cassettes two rows of hooks are provided, which may co-operate with the same lifting means (row of knives).
The characteristics of the shed-forming device according to this invention indicated above are clarified and illustrated and other characteristics and particulars of the invention are indicated in the following, more detailed description of a number of possible embodiments of a shed-forming device and of a shed-forming element according to this invention.
It may be clear that the only purpose of this description is to clarify the invention on the basis of some examples and so in no way may be considered to be a limitation of the scope of this patent application such as it will be stated in the claims enclosed.